David Weir salutes the crowd on the Mall after receiving his gold medal for the wheelchair marathon. Photograph: Tom Jenkins for the Guardian

Beneath cloudless skies, David Weir delivered the final flourish of a glorious summer for British athletes as he stormed to his fourth gold of the Paralympics in the wheelchair marathon.

Minutes later, Shelly Woods sprinted down the Mall to huge cheers to win Britain's 120th Paralympic medal, a silver in the women's event. Their contributions confirmed third place in the medal table for ParalympicsGB, behind China and Russia.

Before a Games that exceeded all expectations in terms of crowds and viewing figures, officials promised to finish second in the table. But they hit their other target of finishing with "more medals in more sports" than in Beijing, where they won 102.

Weir needed every ounce of strength and experience to hold off his Swiss rival Marcel Hug, who conspired with the rest of the pack to try to beat him. It didn't work and Weir said afterwards that the months of work he had put in training with cyclists in Richmond Park had paid off in the gruelling final miles and the flat-out sprint from the Victoria Monument outside Buckingham Palace to the finish.

The 33-year-old, who has six London marathon victories to his name, said it had been the toughest race he had ever taken part in. He said he had looked "moody" as he crossed the line in 1h 30min 20sec – a second ahead of Hug – because he had been unsure where the finish line was.

After receiving his gold medal from Boris Johnson – the London mayor squeezing the last drops out of a summer that has been good to him too – Weir posed for photos with a union flag aloft and his one-year-old son, Mason, on his lap.

The "Weirwolf" will be back on the Mall on Monday as one of the 800 Olympic and Paralympic athletes taking part in a parade of floats expected to be cheered by hundreds of thousands of people from Guildhall to Buckingham Palace.

Weir, who had said he was shattered even before Sunday's 26.2-mile race, praised the crowds who lined the capital's streets. "It was just fantastic, they just give you a lift. My whole body was tingling. When I couldn't even feel my push rims, it was just getting me through." He paid tribute to the group of "50 or 60" family and friends who came to watch, and in particular his pregnant fiancee, Emily Thorne.

"She's a great support. She's very good, keeping me calm and level-headed. She's the one who's made me comfortable speaking in front of the media – just given me a lot of confidence in myself really."

It was the first time Thorne had come to watch him since the first heats of the 5000m. In front of rapturous crowds in the Olympic Stadium, he went on to win not only the 5000m but the 1500m and the 800m as well.

Four years ago Weir won two gold medals on the track in Beijing. Asked about his ambitions for Rio in four years' time, he said he wasn't looking beyond the beaches of Ibiza. A keen bedroom DJ, he was looking forward to a celebratory holiday with a group of friends before his new baby was born.

Woods, who has endured disappointment on the track this summer, said the experience had made her stronger. "These Games have built me as a character. I felt a little bit like Rocky. I kept getting bashed down and I kept jumping up for more. Today I jumped up for more," she said.

Channel 4 again had to defend its coverage after it was unable to provide live pictures of the marathon. As at the cycling road race at Brands Hatch, the official broadcaster, OBS, did not provide a live feed or timing information because, it said, it was not economically viable. So Channel 4, which has attracted audiences of more than 6m for its Paralympics coverage, had to rely on its own cameras at fixed points of the course.

Lord Coe, the London 2012 chairman, said he was convinced that the Paralympics had shifted the attitudes of the nation. "I would like to think that by extending the excitement from the Olympic Games into the Paralympic Games and that exhilaration has led to a greater education," he said. "I think people will leave understanding a great deal more about the world they are living in."